The present invention relates to electro optical systems and, more particularly, to an improved system and method for visualizing objects within a surgical field in aid of microsurgical procedures.
Physicians and especially surgeons have long had the need to see, in detail, minute anatomical structures upon which they wish to operate during the course of a procedure. In many instances, the operating field is sufficiently exposed and accessible so that the naked eye is adequate for the work at hand. When, however, the objects in the field are too small to be easily seen with the naked eye, some form of magnification and micro instrumentation is necessary to permit a visualization of the working area.
Typical examples of procedures which require magnification in order to properly visualize the areas of interest are ear surgery (e.g stapedius mobilization), laryngeal surgery (the removal of tumors), neurosurgery (removal of aneurysms), gynecological surgery (repair divided tubes), urological surgery (anastomosis of a divided vas), hand surgery to suture small tendons, trauma surgery for the reimplantation of amputated extremities, and ophthamological procedures, just to name a few.
For many years, optical instrument makers provided microscopes, both monocular and binocular, which permitted a surgeon to view the surgical field with a selected magnification. Such instruments tend to be large, bulky, and require either a wall or ceiling mounting or a large stand to support the optics without undue vibration. These surgical microscopes were provided with a lens system that permitted some distance between the field (object) and the eyepieces. This distance is necessary so that the surgeon can introduce instruments between the microscope and the object under visual control.
Moreover, such systems required careful alignment and focussing, especially if the depth of field is limited to a plane of approximately one to two millimeter thickness. In addition, an illumination system was required which either projected a spotlight on the field through the optical system or used an external source with a fiber cable that could be attached to the microscope head.
With the advent of surgical microscopes, many so-called microsurgical procedures were attempted successfully, permitting the repair, restoration or implantation of many small organs. Nevertheless, disadvantages include, among other things, the size and weight of the instrument which requires time consuming efforts to adjust and direct it, and the need to accommodate an assistant, which generally requires a second station and a beam splitter with the attendant diminution of the light at the primary eyepiece.
The use of the conventional binocular microscope imposes its own special problems upon the surgeon who must remain more or less immobilized in order to view the field through the binocular eyepieces. Viewing through the small pupil of an eyepiece also causes fatigue in the viewer, especially if the procedure is a long and difficult one.
In many of these microscopes, when beamsplitters are used to provide a second viewing station, to be utilized by an assistant, or for documentation purposes by mounting cameras or the like, the available illumination must be divided among all of the stations. In a purely optical system, each time a beamsplitter is employed, the brightness of the transmitted image is reduced, thereby limiting the number of viewing stations by the extent to which the field can be illuminated. If the light intensity must be increased to provide adequate illumination at each viewing station, then the problem of increased heat must be dealt with and the operating field should not be overheated.
If cameras are utilized for still or motion picture photography, or, as in more modern systems, video cameras are employed which are coupled to videotape machines or video monitors, lower levels of light can be accepted by going to faster films or more sensitive electronic systems. It is, of course, possible to use electronic light amplification techniques with the video system, enabling a record to be made under marginal viewing conditions.
Once the patient is readied, the microscope must be trained on the field of interest and focussed. If any photographs are taken, they will appear substantially "flat" and planar since only a fairly "thin" section is in focus at any given time and if a feature or artifact that is closer or farther from the focal plane is to be viewed, the focus of the microscope must be readjusted. Since the optimum image in a surgeon's eyepiece may not result in the sharpest image for the camera, the focussing procedure may become quite time consuming.
Video cameras have taken a greater role in the surgical operating room with the advent of lighter, smaller and higher resolution sensor systems. To some extent, the mere transmission of an image from the photosensitive transducer area of the video camera to the much larger screen of the monitor provides some degree of magnification with acceptable image resolution.